KenInNC
New Member
Hello! First timer here. I am trying to install my panels this April and I am ordering the PV cable and MC 4 connectors and I wanted to hear if I have my math correct or wrong please.
I am using a Rensola RePlus 8000TL Plus Grid Tie String Inverter and SunPower Performance Series SPR-P17-340-COM panels. I can use either 14 or 15 panels at this portion of the first install and I plan to add the others to bring the power as close to 8000w as possible so I have the choice of using 3 sets of 5 panels in series or 2 sets of 7 panels in series joined as the 1st string to the Inverter (as I believe it can also allow me to add a 2nd final string later (additional 3Kw of panels)).
I will attach the .pdf's of the panels and inverter but to be fast I did my best to enter the direct information for the specific models of each item. I hope this helps.
Quick history. I have my install permit from the county, the 8000w Inverter, 10Kw worth of 340w panels, mounting hardware, Combiner box, emergency disconnects and MC4 M&F connectors. I am getting ready to order Marine Grade 10AWG sheathed two wire (red and black), 2 to 1 and 3 to 1 MC4 combiners connectors, MC4 wrenches. I am debating on a thru the roof to the attic roof openning versus a long run of direct exposed cable (in proper outdoor gray plastic EMT pipe). I am open to any suggestions. I will try to post a rough drawing of my roof layout and limited panel placement and hopefully number the panels to make anyone's explanation easier to do. Thank you for reading this far as I am a long winded type of guy who tries to provide the most information the first time around.
My concerns are:
1. I am trying to order some 2:1 and 3:1 MC4 pair branch connectors before the delivery starts getting worse with this Covid 19 (I want to get the order right the first time). I will be running 10AWG Marine Grade wire for all connections.
2. I don't understand the start voltage for the inverter. Does this mean that the rated start voltage of 360Vdc needs my string from 14-15 42.5Vdc panels to add up to at least the 360Vdc or more but not more than 600Vdc? I was thinking of doing three sets of five panels which has a combined series and final parallel voltage total of 212.5Vdc at 24 A. So I guess this does not work?
3. Should I focus on getting a series of panels to add up to at least 360Vdc and is the higher voltage the better up to 600Vdc? This may limit what I can put to the inverter as I was told that two strings going into the inverter should match voltage as close as possible between the two strings. Is this correct too?
4. With 15 panels, I can combine 8 for a series Vdc total of 340Vdc and combine the other 7 for a series Vdc total of 297.5 (all under optimum conditions of course) but this sounds like the inverter will not even start with this Vdc power incoming plus the two sets of incoming would be what ... roughly 320Vdc at 16 A? Suggestions? I am really confused here.
Bottom line is that I am so confused with this whole organization of how many panels should be in SERIES and how many SETS should be in PARALLEL before going to the inverter as one string or two strings and still use my 14-15 panels effeciently and have the system work. I think I have over read and looked at too many webpages to the point that its starting to get blurry. I have no idea of what other information to give so please let me know what I need to tell you or if you have a suggestion on connecting this setup and thank you.
Inverter INPUT (DC)
Max. DC power: 8300W
Max. DC voltage: 600V
Start voltage: 360V
DC rated voltage: 345V @208Vac and 379V @240Vac
PV voltage range: 300-600V @208Vac 345-600V @240Vac
MPP voltage range: 300-480V @208Vac 345-480V @240Vac
Max. input current: 30A
Max. input current per string: 30A
Number of MPP trackers/ strings per MPP tracker: 1/2
Inverter OUTPUT (AC)
Nominal AC output power: 8000W
Max. output current: 44A @208Vac 38A @220Vac
AC Nominal voltage/range: 208V / 183-229V, 240V /211-264v
AC grid frequency; range: 60Hz / 59.3-60.5 Hz
Power factor: 1
THDI: <3%
Consumption: operating (standby) / night: <5W / <0.5W
SOLAR PANELS (Multicrystalline cells)
Nominal Power (Pnom): 340 W
Power Tolerance: +5/−0%
Efficiency: 16.5%
Rated Voltage (Vmpp): 42.5 V
Rated Current (Impp): 8.00 A
Open-Circuit Voltage (Voc): 51.3 V
Short-Circuit Current (Isc): 8.52 A
Power Temp. Coef.: -174.4mV/° C
Voltage Temp. Coef.: 3.6mA/° C
Current Temp. Coef.: 1000V UL & 1000V IEC
Maximum System Voltage Maximum Series Fuse: 15A
I am using a Rensola RePlus 8000TL Plus Grid Tie String Inverter and SunPower Performance Series SPR-P17-340-COM panels. I can use either 14 or 15 panels at this portion of the first install and I plan to add the others to bring the power as close to 8000w as possible so I have the choice of using 3 sets of 5 panels in series or 2 sets of 7 panels in series joined as the 1st string to the Inverter (as I believe it can also allow me to add a 2nd final string later (additional 3Kw of panels)).
I will attach the .pdf's of the panels and inverter but to be fast I did my best to enter the direct information for the specific models of each item. I hope this helps.
Quick history. I have my install permit from the county, the 8000w Inverter, 10Kw worth of 340w panels, mounting hardware, Combiner box, emergency disconnects and MC4 M&F connectors. I am getting ready to order Marine Grade 10AWG sheathed two wire (red and black), 2 to 1 and 3 to 1 MC4 combiners connectors, MC4 wrenches. I am debating on a thru the roof to the attic roof openning versus a long run of direct exposed cable (in proper outdoor gray plastic EMT pipe). I am open to any suggestions. I will try to post a rough drawing of my roof layout and limited panel placement and hopefully number the panels to make anyone's explanation easier to do. Thank you for reading this far as I am a long winded type of guy who tries to provide the most information the first time around.
My concerns are:
1. I am trying to order some 2:1 and 3:1 MC4 pair branch connectors before the delivery starts getting worse with this Covid 19 (I want to get the order right the first time). I will be running 10AWG Marine Grade wire for all connections.
2. I don't understand the start voltage for the inverter. Does this mean that the rated start voltage of 360Vdc needs my string from 14-15 42.5Vdc panels to add up to at least the 360Vdc or more but not more than 600Vdc? I was thinking of doing three sets of five panels which has a combined series and final parallel voltage total of 212.5Vdc at 24 A. So I guess this does not work?
3. Should I focus on getting a series of panels to add up to at least 360Vdc and is the higher voltage the better up to 600Vdc? This may limit what I can put to the inverter as I was told that two strings going into the inverter should match voltage as close as possible between the two strings. Is this correct too?
4. With 15 panels, I can combine 8 for a series Vdc total of 340Vdc and combine the other 7 for a series Vdc total of 297.5 (all under optimum conditions of course) but this sounds like the inverter will not even start with this Vdc power incoming plus the two sets of incoming would be what ... roughly 320Vdc at 16 A? Suggestions? I am really confused here.
Bottom line is that I am so confused with this whole organization of how many panels should be in SERIES and how many SETS should be in PARALLEL before going to the inverter as one string or two strings and still use my 14-15 panels effeciently and have the system work. I think I have over read and looked at too many webpages to the point that its starting to get blurry. I have no idea of what other information to give so please let me know what I need to tell you or if you have a suggestion on connecting this setup and thank you.
Inverter INPUT (DC)
Max. DC power: 8300W
Max. DC voltage: 600V
Start voltage: 360V
DC rated voltage: 345V @208Vac and 379V @240Vac
PV voltage range: 300-600V @208Vac 345-600V @240Vac
MPP voltage range: 300-480V @208Vac 345-480V @240Vac
Max. input current: 30A
Max. input current per string: 30A
Number of MPP trackers/ strings per MPP tracker: 1/2
Inverter OUTPUT (AC)
Nominal AC output power: 8000W
Max. output current: 44A @208Vac 38A @220Vac
AC Nominal voltage/range: 208V / 183-229V, 240V /211-264v
AC grid frequency; range: 60Hz / 59.3-60.5 Hz
Power factor: 1
THDI: <3%
Consumption: operating (standby) / night: <5W / <0.5W
SOLAR PANELS (Multicrystalline cells)
Nominal Power (Pnom): 340 W
Power Tolerance: +5/−0%
Efficiency: 16.5%
Rated Voltage (Vmpp): 42.5 V
Rated Current (Impp): 8.00 A
Open-Circuit Voltage (Voc): 51.3 V
Short-Circuit Current (Isc): 8.52 A
Power Temp. Coef.: -174.4mV/° C
Voltage Temp. Coef.: 3.6mA/° C
Current Temp. Coef.: 1000V UL & 1000V IEC
Maximum System Voltage Maximum Series Fuse: 15A